Sample Size and Power of Randomized Designs
Feifang Hu
Statistics, University of Virginia
| Time:
01:00pm - 02:00pm |
Location: MP 401 |
Abstract:
Randomized designs are often used in clinical trials.
In the literature, the power and sample size are usually
obtained by ignoring the randomness of the allocation in
randomized designs. However, when using a randomized
design, the power is a random variable for a fixed sample
size $n$. In this talk, we focus on the power function
(random) and the sample size of two-arm (drug versus control)
randomized clinical trials. We first give an example
where a target power can not be achieved with high
probability when the requisite sample size (based on the
formula in the literature) is used. Then we obtain the power
function for any given sample size and study the properties
of this power function. Based on the power function,
a formula of sample size is derived for randomized designs.
This formula is applied to several randomization procedures.
We also discuss our finding that response adaptive designs
can be used to reduce the requisite sample size.
Some simulation studies are reported.
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